1. Hardware-efficient quantum error correction via concatenated bosonic qubits.
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Putterman H, Noh K, Hann CT, MacCabe GS, Aghaeimeibodi S, Patel RN, Lee M, Jones WM, Moradinejad H, Rodriguez R, Mahuli N, Rose J, Owens JC, Levine H, Rosenfeld E, Reinhold P, Moncelsi L, Alcid JA, Alidoust N, Arrangoiz-Arriola P, Barnett J, Bienias P, Carson HA, Chen C, Chen L, Chinkezian H, Chisholm EM, Chou MH, Clerk A, Clifford A, Cosmic R, Curiel AV, Davis E, DeLorenzo L, D'Ewart JM, Diky A, D'Souza N, Dumitrescu PT, Eisenmann S, Elkhouly E, Evenbly G, Fang MT, Fang Y, Fling MJ, Fon W, Garcia G, Gorshkov AV, Grant JA, Gray MJ, Grimberg S, Grimsmo AL, Haim A, Hand J, He Y, Hernandez M, Hover D, Hung JSC, Hunt M, Iverson J, Jarrige I, Jaskula JC, Jiang L, Kalaee M, Karabalin R, Karalekas PJ, Keller AJ, Khalajhedayati A, Kubica A, Lee H, Leroux C, Lieu S, Ly V, Madrigal KV, Marcaud G, McCabe G, Miles C, Milsted A, Minguzzi J, Mishra A, Mukherjee B, Naghiloo M, Oblepias E, Ortuno G, Pagdilao J, Pancotti N, Panduro A, Paquette JP, Park M, Peairs GA, Perello D, Peterson EC, Ponte S, Preskill J, Qiao J, Refael G, Resnick R, Retzker A, Reyna OA, Runyan M, Ryan CA, Sahmoud A, Sanchez E, Sanil R, Sankar K, Sato Y, Scaffidi T, Siavoshi S, Sivarajah P, Skogland T, Su CJ, Swenson LJ, Teo SM, Tomada A, Torlai G, Wollack EA, Ye Y, Zerrudo JA, Zhang K, Brandão FGSL, Matheny MH, and Painter O
- Abstract
To solve problems of practical importance
1,2 , quantum computers probably need to incorporate quantum error correction, in which a logical qubit is redundantly encoded in many noisy physical qubits3-5 . The large physical-qubit overhead associated with error correction motivates the search for more hardware-efficient approaches6-18 . Here, using a superconducting quantum circuit19 , we realize a logical qubit memory formed from the concatenation of encoded bosonic cat qubits with an outer repetition code of distance d = 5 (ref.10 ). A stabilizing circuit passively protects cat qubits against bit flips20-24 . The repetition code, using ancilla transmons for syndrome measurement, corrects cat qubit phase flips. We study the performance and scaling of the logical qubit memory, finding that the phase-flip correcting repetition code operates below the threshold. The logical bit-flip error is suppressed with increasing cat qubit mean photon number, enabled by our realization of a cat-transmon noise-biased CX gate. The minimum measured logical error per cycle is on average 1.75(2)% for the distance-3 code sections, and 1.65(3)% for the distance-5 code. Despite the increased number of fault locations of the distance-5 code, the high degree of noise bias preserved during error correction enables comparable performance. These results, where the intrinsic error suppression of the bosonic encodings enables us to use a hardware-efficient outer error-correcting code, indicate that concatenated bosonic codes can be a compelling model for reaching fault-tolerant quantum computation., Competing Interests: Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)- Published
- 2025
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